1. Field of the Invention
The present invention relates to a headrest for use on an automotive seat, of the type formed under a foaming process wherein a headrest frame is inserted into a three-dimensional trim cover assembly of a given headrest shape, through an opening defined therein, and then a liquid foaming base material is injected in the trim cover assembly, for foaming integrally the frame and trim cover assembly together. More particularly, the present invention is directed to a donut-like or generally annular headrest having a through-hole therein, which is formed by the foaming process of this kind.
2. Description of Prior Art
In a foaming process for forming a donut-like or annular headrest for use on an automotive seat, there is a step that requires using a generally annular shape of headrest frame with headrest stay(s) and inserting it into and along the annular hollow inside of a preformed three-dimensional donut-like trim cover assembly. Subsequent thereto, a liquid foaming base material is injected in that trim cover assembly and cured therein together with the headrest frame, so that a resulting foamed donut-like unit of headrest is obtained, with the headrest stay(s) projected therefrom.
This process, however, has encountered a technical difficulty in terms of how the annular headrest frame can be easily placed in the preformed donut-like trim cover assembly for the subsequent foaming process. Some solutions to this problem have been made as for example disclosed from the Japanese Laid-Open Patent Pub. Nos. 62-257818 and 9-271425, and also from the Japanese Granted Patent Pub. No. 4-401818. These prior art patents commonly suggest that a generally inverted-U-shaped headrest frame with headrest stays be inserted in the preformed donut-like trim cover assembly, and then, a connecting frame be connected between two side frame sections of such headrest frame, to thereby provide an annular frame portion extending in and along the donut-like trim cover assembly, after which, a foaming is effected to create a foam padding integrally with those frames and trim cover assembly, so that a resulting donut-like headrest is obtained.
But, such solution has been found defective in that the connecting frame can not be quickly and precisely assembled with the headrest frame, because a worker can hardly see the connecting point between the connecting and headrest frames which are both located in the trim cover assembly and must connect together those two frames within the trim cover assembly, by feeling them with his or her hands.
To overcome that drawback, it may be suggested that the connecting frame be connected with the headrest frame, outside of the trim cover assembly, as for example known from the Japanese Granted U.M. Pub. No. 7-31724. According to this prior art, a plate-like connecting frame is provided, which has a slit formed therein. During assembly, a generally U-shaped headrest frame is inserted into an opening of donut-like trim cover assembly and placed in the trim cover assembly through that opening, while projecting two headrest stay sections of the frame outwardly therefrom, and thereafter, the plate-like connecting frame is connected between the two projected headrest stay sections, while inserting the ends of the foregoing opening of the trim cover assembly into and through the slit of the connecting frame. In that way, the connecting frame can easily be accessed and connected to the headrest frame, externally of the trim cover assembly, in order to provide an annular framework in conformity with the donut-like trim cover assembly and also close the opening of the same trim cover assembly.
However, in this second prior art, the slit of connecting frame is formed rather narrow with a view to preventing leakage of a liquid foaming base material from between the slit and the ends of the opening, as a result of which, it is troublesome and time-consuming for a worker to squeeze and insert the ends of the opening into such narrow slit during assembly. Further, this sealing is rather rough, so that in the foaming process, a liquid foaming base material injected in the trim cover assembly will invade into non-tight spots between the connecting frame and ends of opening, and result in creating an objectionable uneven or irregular spots in the outer surface of resulting headrest after foaming process, which impairs the aesthetic appearance of headrest.